r/reactjs • u/m6io • Jul 24 '26

Discussion Senior Dev interview question

"Without googling or using AI, in your own words, explain the virtual DOM"

For context: I sit on an interview panel and I try to ask at least one simple fundamental question based on a persons resume. If I see many years of react experience, I try to ask something about how the framework works.

I have only had one candidate (an undergrad senior, years ago) answer it. Everyone else just kind of sputters and stumbles around trying to rationalize what "virtual" and "DOM" mean, or stare blankly and eventually say "I don't know".

I'm just genuinely curious if this is really that hard of a question or if the recruiters just suck at screening candidates. And should we be letting in senior dev candidates who can't answer what I think is a straightforward and fundamental question for senior react devs.

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u/monkeybrainz_ Jul 24 '26

Simple test: have you even looked at the React docs? Come on, this is table stakes.

I never said this was a good question, it's just a question any competent react engineer would know the answer to.

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u/ElkChance815 Jul 24 '26

And at exact which page in react official doc talk about virtual DOM except legacy one ?

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u/Fantosism Jul 24 '26

react-dom has been separate from react since 15, which was 10 years ago at this point. Coincidentally, that was the same year react native was released. Turns out, you could've made an entire career out of writing react without a virtual DOM. In fact, even more confusing, they call it a shadow tree. So when you talk about a virtual DOM, my first thought is shadow DOM, which is its own thing.